[Bug libstdc++/52702] New: [C++11] std::is_trivially_destructible is missing

[Bug libstdc++/52702] New: [C++11] std::is_trivially_destructible is missing

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

             Bug #: 52702
           Summary: [C++11] std::is_trivially_destructible is missing
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: daniel.kruegler@googlemail.com


gcc 4.8.0 20120318 (experimental) in C++11 mode rejects the following code:

//-----
#include <type_traits>

struct pod {};
struct non_pod { ~non_pod(); };

static_assert(std::is_trivially_destructible<pod>::value, "");
static_assert(std::is_trivially_destructible<int>::value, "");
static_assert(!std::is_trivially_destructible<non_pod>::value, "");
//-----

due to the missing definition of the is_trivially_destructible type trait.

This should not be much work, because the TR1 trait has_trivial_destructor does
exist and uses the __has_trivial_destructor intrinsic and is_destructible is
also provided.

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-04-12
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
   Target Milestone|---                         |4.8.0
     Ever Confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-12 12:22:10 UTC ---
Ok, thanks.

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-15 13:43:51 UTC ---
Daniel I'm adding this.

By the way, is "is_nothrow_destructible" doable just now or needs compiler
support? Are you willing to give it a try, in case? (or, if necessary, I can do
the compiler bits) It would complete our implementation of the is_nothrow_*
set.

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

--- Comment #3 from Daniel Krügler <daniel.kruegler at googlemail dot com> 2012-04-15 14:05:43 UTC ---
(In reply to comment #2)
> Daniel I'm adding this.
> 
> By the way, is "is_nothrow_destructible" doable just now or needs compiler
> support? Are you willing to give it a try, in case? (or, if necessary, I can do
> the compiler bits) It would complete our implementation of the is_nothrow_*
> set.

The reason why I did not suggested it for the moment is simply because LWG
issue

http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#2049

is still open. Actually, the correct solution for no_throw_destructible depends
on the P/R as well. Of-course one could simply start with a partial solution
(e.g. handle uncontroversial types like reference types, non-function, and
non-abstract types), but I'm not sure whether it is worth the effort. If you
would like to have just an consistent current trait matching to the current
is_destructible implementation, I can work on that. Roughly about the mid of
up-coming week would seem reasonable for me to start on that.

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-15 14:30:19 UTC ---
Ah, I see, I didn't know about that DR.

Then, sure, whenever you like it would be great if you could contribute
is_nothrow_destructible too: should not be much more controversial than
is_destructible itself (which you contributed already and I'm going to use for
is_trivially_destructible of course)

Let's keep in touch!

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-15 17:05:18 UTC ---
Maybe we can ask here Jason about std::is_trivially_copyable, which he didn't
do at once with std::is_trivial (maybe the concept didn't precisely exist at
the time, I don't remember).

Anyway, I see two options: either "exporting" just now from the front-end an
__is_trivially_copyable (just using trivially_copyable_p); or postpone the task
to when std::is_trivially_constructible and std::is_trivially_assignable will
be available, in turn requiring front-end support, but then useful for all the
missing std::is_trivial* things, if I understand correctly.

The former could make sense per se, could also be immediately exploited to
implement std::is_trivially_default_constructible. At some point, anyway, we'll
have to tackle std::is_trivially_constructible and std::is_trivially_assignable
(the former, in particular, with its variadic parameter, seems non-trivial to
me)

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-15 17:48:21 UTC ---
Scratch the std::is_trivially_default_constructible bit, sorry.

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

--- Comment #7 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-04-15 23:35:33 UTC ---
Author: paolo
Date: Sun Apr 15 23:35:27 2012
New Revision: 186474

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186474
Log:
2012-04-15  Paolo Carlini  <paolo.carlini@oracle.com>

    PR libstdc++/52702
    * include/std/type_traits (is_trivially_destructible): Add.
    (has_trivial_destructor): Remove.
    * testsuite/util/testsuite_common_types.h: Adjust.
    * testsuite/20_util/tuple/requirements/dr801.cc: Likewise.
    * testsuite/20_util/pair/requirements/dr801.cc: Likewise.
    * testsuite/20_util/is_trivially_destructible/value.cc: New.
    * testsuite/20_util/is_trivially_destructible/requirements/
    typedefs.cc: Likewise.
    * testsuite/20_util/is_trivially_destructible/requirements/
    explicit_instantiation.cc: Likewise.
    * testsuite/20_util/make_signed/requirements/typedefs_neg.cc:
    Adjust dg-error line numbers.
    * testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc:
    Likewise.
    * testsuite/20_util/declval/requirements/1_neg.cc: Likewise.

Added:
    trunk/libstdc++-v3/testsuite/20_util/is_trivially_destructible/
   
trunk/libstdc++-v3/testsuite/20_util/is_trivially_destructible/requirements/
   
trunk/libstdc++-v3/testsuite/20_util/is_trivially_destructible/requirements/explicit_instantiation.cc
   
trunk/libstdc++-v3/testsuite/20_util/is_trivially_destructible/requirements/typedefs.cc
    trunk/libstdc++-v3/testsuite/20_util/is_trivially_destructible/value.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/std/type_traits
    trunk/libstdc++-v3/testsuite/20_util/declval/requirements/1_neg.cc
   
trunk/libstdc++-v3/testsuite/20_util/make_signed/requirements/typedefs_neg.cc
   
trunk/libstdc++-v3/testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc
    trunk/libstdc++-v3/testsuite/20_util/pair/requirements/dr801.cc
    trunk/libstdc++-v3/testsuite/20_util/tuple/requirements/dr801.cc
    trunk/libstdc++-v3/testsuite/util/testsuite_common_types.h

[Bug libstdc++/52702] [C++11] std::is_trivially_destructible is missing

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52702

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-04-22 08:05:18 UTC ---
Done.